The present invention relates to an electronics device which comprises a carrier, such as a printed circuit board, a substrate or a chip, and an electric conductor on one surface of the carrier.
Electronics devices such as printed circuit boards, substrates or chips contain different forms of conductor structures. The conductor structures are to be found on the surfaces of or inside said devices. The conductor structures are used to electrically join different components or integrated structures or to connect the device to the surroundings.
Conductor structures of printed circuit boards, substrates or chips consist of conductors which are essentially rectangular in cross-section. Deviations from the rectangular shape depend on the process that is used to manufacture the conductor structure.
An ever increasing working frequency is required in today""s electronics products. This causes a number of problems such as high specific resistance, impedance, depending on the skin effect, which implies that the current is essentially carried at the circumferential surface of the conductor.
Moreover, an increasing number of products are designed requiring an increasing current density in the conductors. This causes considerable generation of heat in the conductors, which results in higher temperatures in the conductors. Besides, for different reasons use is made in many electronics constructions of conductor materials which are not the optimal ones in view of electric conducting capacity. In the future it will probably, owing to greater environmental considerations and increased integration requirements, be more common that materials that do not have optimal electrical conducting properties are used in conductor structures.
A further problem with the conductors of today""s electronics devices is that it may be difficult to solder components to the conductors or mounting islands connected to the conductors.
An object of the present invention is to provide an electronics device with an electric conductor having improved properties for high current densities and high frequencies.
A further object of the present invention is to provide an electronics device with conductor structures which improve the possibilities of soldering other components.
These objects are achieved by an electronics device comprising a carrier, such as a printed circuit board, a substrate or a chip, and an electric conductor on a surface of the carrier, characterized in that the surface of the conductor facing away from the carrier has a surface structure in the form of flanges which are defined by etched grooves.
By electronics device is meant a device which comprises at least one conductor.
An electronics device according to the invention comprises a carrier, such as a printed circuit board, a substrate or a chip, and an electric conductor on a surface of the carrier. The electronics device is characterised in that the surface of the conductor facing away from the carrier has a surface structure in the form of flanges which are defined by etched grooves.
The conductor is preferably arranged on a non-metallic surface of the carrier.
According to one aspect of the invention, patterns or surface structures in the conductors are made smaller than the circumferential dimensions of the conductors by using an anisotropic etching method. These patterns or surface structures may consist of, for instance, longitudinal etched flanges. As a result, the heat-emitting surface of the conductors increases from the conductor. One more advantage of the invention is that it permits improved mechanical strength in joints between the conductor and other components which are, for example, fixed to the conductor by soldering or gluing with an electrically conductive glue. The improved strength depends on the increased surface in the joint.
Preferably the flanges are arranged in the longitudinal direction of the conductor. This results in the further advantage that the electric resistance decreases at high frequencies. The skin effect, which means that the current is essentially carried at the circumferential surface of a conductor at high frequencies, causes the electric resistance to increase at high frequencies. This reduction is compensated for by the increased surface of the conductor.
If merely improvement of the heat emission is desired, the flanges may extend transversely of the conductor direction.
When the flanges are oriented in the longitudinal direction of the conductor, the depth of the grooves is preferably smaller than the thickness of the conductor perpendicularly to the surface, but the grooves can also extend over the entire thickness of the conductor, thereby dividing the conductor into separate subconductors.
In the case where the conductor is divided into separate subconductors, they are preferably connected to at least one conductor portion extending in the transverse direction.
When components are to be connected to the conductors, it is advantageous for the conductors to be connected to so-called connection areas. The components are soldered or glued with an electrically conductive glue to the connection area. With a view to improving the mechanical strength in the glue or soldering joint, it is advantageous to provide the surface of the connection area with a surface structure.
The surface structure of the connection area is advantageously produced by etching.
After etching, a non-conductive layer can be arranged on the etched surface. When the device is a printed circuit board, the non-conductive layer may consist of, for instance, a coating film intended to protect the conductor. When the device is an integrated circuit, the non-conductive layer may consist of, for instance, a protective oxide film.
It goes without saying that the above features can be combined in the same embodiment.
In order to further elucidate the invention, detailed embodiments thereof will be described below, without, however, the invention being considered to be restricted thereto.